Lens driving device, camera module and optical apparatus

ABSTRACT

A lens driving device is provided, including: a holder member; a bobbin disposed at an inner side of the holder member; a magnet disposed at the holder member; a first coil unit disposed at the bobbin, and facing the magnet; a first support member coupled to the holder member and the bobbin; and a detection sensor disposed at the bobbin, and configured to detect magnetic force of the magnet, wherein the magnet includes a facing surface and an opposite surface disposed at an opposite side of the facing surface, wherein a polarity of the facing surface and a polarity of the opposite surface are different from each other, wherein a polarity of an upper portion of the facing surface and a polarity of a lower portion of the facing surface are different from each other. According to an embodiment, Hall output detected by the detection sensor can be enhanced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/004,449, filed Jan. 22, 2016, which claims the benefit under 35U.S.C. § 119 of Korean Application No. 10-2015-0010314, filed Jan. 22,2015, the disclosures of each of which are incorporated herein byreference in their entirety.

BACKGROUND OF THE DISCLOSURE Technical Field

The present exemplary embodiments relate to a lens driving device, acamera module and an optical apparatus.

Background

The technology described in this section is merely intended to providebackground information of an exemplary embodiment of the presentdisclosure, and does not mean the prior art.

A camera module may include an image sensor, a PCB (Printed CircuitBoard) configured to deliver electric signals to the image sensorinstalled on the PCB, an infrared cut-off filter configured to blocklight in infrared area from being incident on the image sensor, and anoptical system including at least one lens configured to deliver animage to the image sensor. Here, a lens driving device configured toperform auto-focusing function and handshake compensation function maybe installed in the optical system.

The lens driving device may be composed in a variety of ways. Ingeneral, a voice coil motor is commonly used in the lens driving device.The VCM (Voice Coil Motor) operates by an electromagnetic interactionbetween a magnet fixed in a housing and a coil unit wound on an outercircumferential surface of a bobbin coupled with a lens barrel. The VCMmay perform auto-focusing function. An actuator module of such VCM mayreciprocatively move in a direction parallel to an optical axis while abobbin being moved in upward and downward directions is elasticallysupported by an upper and a first elastic member.

Recently, there has been a requirement to develop a lens driving deviceconfigured to swiftly detect an optimal focus position by receivingposition information of a bobbin installed with a lens as a feedback.

However, in a case where a detection unit such as a Hall sensor isinstalled for feedback, the positioning of the Hall sensor may bedifficult. Such feature of the conventional art is required to beimproved.

BRIEF SUMMARY

According to an exemplary embodiment, a lens driving device having autofocus and handshake compensation functions is provided, the lens drivingdevice is capable of receiving accurate position information of a bobbinand a holder member as feedbacks.

In a general aspect, there is provided a lens driving device, the lensdriving device comprising: a bobbin installed ascendable and descendiblein relation to an optical axis, where a coil unit is wound on an outercircumferential surface of the bobbin; a holder member including amagnet arranged at a position facing the coil unit; an upper elasticmember and a lower elastic member elastically supporting the bobbin,where one end of each of the upper elastic member and the lower elasticmember is connected to the bobbin and another end of each of the upperelastic member and the lower elastic member is connected to the holdermember; and a detection sensor arranged at a position facing the magnetof the bobbin and detecting change in magnetic force of the magnet dueto displacement of the bobbin, wherein a surface of the magnet facingthe bobbin and a surface of the magnet opposite to the surface facingthe bobbin may be magnetized in polarities different from each other,and an upper portion of the magnet and a lower portion of the magnet maybe magnetized in lengths and polarities different from each other.

In some exemplary embodiments, the magnet may include: a first magnetportion and a second magnet portion respectively arranged at an upperportion of the magnet; and a third magnet portion and a fourth magnetportion respectively arranged at a lower portion of the magnet, whereinsizes of the third magnet portion and the fourth magnet portion mayformed larger than sizes of the first magnet portion and the secondmagnet portion.

In some exemplary embodiments, a size of the first magnet portion may beformed equal to a size of the second magnet portion, and a size of thethird magnet portion may be formed equal to a size of the fourth magnetportion.

In some exemplary embodiment, a polarity of the first magnet portion maybe same as a polarity of the fourth magnet portion, and a polarity ofthe second magnet portion may be same as a polarity of the third magnetportion.

In some exemplary embodiment, a polarity of the first magnet portion maybe opposite to a polarity of the third magnet portion, and a polarity ofthe second magnet portion may be opposite to a polarity of the fourthmagnet portion.

In some exemplary embodiments, each of the first magnet portion and thefourth magnet portion may have an N-polarity, and each of the secondmagnet portion and the third magnet portion may have an S-polarity.

In some exemplary embodiments, the detection sensor may be arranged at aposition facing the second magnet portion and the fourth magnet portion,and may be center-aligned to a boundary line between the second magnetportion and the fourth magnet portion.

In some exemplary embodiments, a center of a sensing surface of thedetection sensor may be aligned to a boundary line between the secondmagnet portion and the fourth magnet portion.

In some exemplary embodiments, the detection sensor may be a Hallsensor.

In another general aspect, there is provided a camera module, the cameramodule may comprise: an image sensor, a printed circuit board installedwith the image sensor; and a lens driving device configured as describedin the above.

In still another general aspect, there is provided a lens drivingdevice, the lens driving device comprising: a holder member; a bobbindisposed at an inner side of the holder member; a magnet disposed at theholder member; a first coil unit disposed at the bobbin, and facing themagnet; a first support member coupled to the holder member and thebobbin; and a detection sensor disposed at the bobbin, and detectingmagnetic force of the magnet, wherein the magnet may include a facingsurface facing the bobbin and an opposite surface disposed at anopposite side of the facing surface, wherein a polarity of the facingsurface and a polarity of the opposite surface may be different fromeach other, and wherein a polarity of an upper portion of the facingsurface and a polarity of a lower portion of the facing surface may bedifferent from each other.

In some exemplary embodiments, the magnet may include a first magnetportion disposed at an outer upper portion and having a first polarity,a second magnet portion disposed at an inner upper portion and having asecond polarity different from the first polarity, a third magnetportion disposed at an outer lower portion and having the secondpolarity, and a fourth magnet portion disposed at an inner lower portionand having the first polarity.

In some exemplary embodiments, lengths in up and down directions of thefirst magnet portion and the second magnet portion may be shorter thanlengths in up and down directions of the third magnet portion and thefourth magnet portion.

In some exemplary embodiments, widths of the first magnet portion andthe third magnet portion may correspond to widths of the second magnetportion and the fourth magnet portion.

In some exemplary embodiments, a size of the first magnet portion maycorrespond to a size of the second magnet portion, and a size of thethird magnet portion may correspond to a size of the fourth magnetportion.

In some exemplary embodiments, each of the first magnet portion and thefourth magnet portion may have an N-polarity, and each of the secondmagnet portion and the third magnet portion may have an S-polarity.

In some exemplary embodiments, the detection sensor may face at leastone of the second magnet portion and the fourth magnet portion.

In some exemplary embodiments, the detection sensor may be disposed on avirtual straight line extended from a boundary line between the secondmagnet portion and the fourth magnet portion.

In some exemplary embodiments, a center of a sensing portion of thedetection sensor may be disposed on a virtual straight line extendedfrom a boundary line between the second magnet portion and the fourthmagnet portion, in an initial state where electric power is not suppliedto the first coil unit.

In some exemplary embodiment, the first coil unit and the detectionsensor may be disposed at an outer circumferential surface of thebobbin, and the detection sensor may be disposed at an upper side of thefirst coil unit.

In some exemplary embodiments, the magnet may be fixed to an innerlateral surface of the holder member, and the first coil unit may befixed to an outer lateral surface of the bobbin.

In some exemplary embodiments, the lens driving device may furthercomprise: a base disposed at a lower side of the holder member; a firstcircuit board disposed at an upper surface of the base; a second coilunit electrically conducted to the first circuit board, and facing themagnet; and a second support member supporting the holder member inrelation to the base.

In some exemplary embodiments, the lens driving device may furthercomprise: a second circuit board installed with the detection sensor,and disposed at the bobbin, wherein the second circuit board may beelectrically conducted to the first support member, the second supportmember, and the first circuit board.

In some exemplary embodiments, the facing surface and the oppositesurface may be magnetized in polarities different from each other, andan upper portion of the magnet and a lower portion of the magnet may bemagnetized in lengths and polarities different from each other.

In still another general aspect, there is provided a camera module, thecamera module comprising: a holder member; a bobbin disposed at an innerside of the holder member; a magnet disposed at the holder member; afirst coil unit disposed at the bobbin, and facing the magnet; a firstsupport member coupled to the holder member and the bobbin; and adetection sensor disposed at the bobbin, and configured to detectmagnetic force of the magnet, wherein the magnet may include a facingsurface facing the bobbin and an opposite surface disposed at anopposite side of the facing surface, wherein a polarity of the facingsurface and a polarity of the opposite surface may be different fromeach other, and wherein a polarity of an upper portion of the facingsurface and a polarity of a lower portion of the facing surface may bedifferent from each other.

In still another general aspect, there is provided an optical apparatus,the optical apparatus comprising: a holder member; a bobbin disposed atan inner side of the holder member; a magnet disposed at the holdermember; a first coil unit disposed at the bobbin, and facing the magnet;a first support member coupled to the holder member and the bobbin; anda detection sensor disposed at the bobbin, and configured to detectmagnetic force of the magnet, wherein the magnet may include a facingsurface facing the bobbin and an opposite surface disposed at anopposite side of the facing surface, wherein a polarity of the facingsurface and a polarity of the opposite surface may be different fromeach other, and wherein a polarity of an upper portion of the facingsurface and a polarity of a lower portion of the facing surface may bedifferent from each other.

According to an exemplary embodiment, the magnet can be configured inasymmetric magnetization. Therefore, the Hall sensor may be arranged ata center position where the N-pole and the S-pole intersect with eachother to set an initial position. Thereby, assemblability of the productcan be enhanced.

In addition, according to an exemplary embodiment, a bipolar-magnetizedmagnet may be used. Thereby, higher Hall output can be obtained.

In addition, according to an exemplary embodiment, the asymmetric magnetallows use of a unidirectional coil unit. Therefore, it is advantageousfor winding up of the coil unit.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic perspective view illustrating a camera moduleaccording to an exemplary embodiment.

FIG. 2 is an exploded perspective view of FIG. 1.

FIG. 3 is a cross-sectional view illustrating a lens driving deviceaccording to an exemplary embodiment.

DETAILED DESCRIPTION

Hereinafter, some exemplary embodiments will be described with referenceto the exemplary drawings. In designating elements in the drawings asreference numerals, wherever possible, the same reference numerals areused to refer to the same element, even though the same elements areillustrated in different drawings. In addition, in describing exemplaryembodiments of the present disclosure, when it is determined that adetailed description about known function or structure relating to thepresent disclosure may disturb understanding of exemplary embodiments ofthe present disclosure, the detailed description may be omitted.

In addition, in describing elements of exemplary embodiments of thepresent disclosure, the terms such as “first”, “second” “A”, “B”, “(a)”and “(b)” may be used. However, such terms are used merely todistinguish a particular element from another element, and therefore,essence, order or sequence of the relevant elements shall not be limitedby the terms. It will be understood that when an element is referred toas being “connected”, “contacted” or “coupled” to another element, itcan be directly connected, contacted or coupled to the other elements,or otherwise, an intervening elements may be “connected”, “contacted” or“coupled” between the element and the other element.

As used herein, the term “optical axis direction” is defined as adirection of an optical axis of a lens module installed at a lensactuator. Meanwhile, the term “optical axis direction” may be used incombination with the terms such as “up/down direction”, “z-axisdirection”, etc.

As used herein, the term “auto focus function” is defined as a functionto focus on the subject by moving the lens module in the optical axisdirection according to distance to the subject to adjust the distancebetween an image sensor and the subject, in order to form a clear imageon the image sensor. Meanwhile, the term “auto focus” may be used incombination with the term “AF (Auto Focus)”.

As used herein, the term “handshake compensation function” is defined asa function to move or tilt the camera module in a directionperpendicular to the optical axis direction so as to counterbalancetrembling (motion) generated by the image sensor due to external force.Meanwhile, the term “handshake compensation” may be used in combinationwith the term “OIS (Optical Image Stabilization)”.

Hereinafter, a structure of an optical apparatus according to anexemplary embodiment will be described.

An optical apparatus according to an exemplary embodiment may be any oneof a mobile phone, a smart phone, a portable smart device, a digitalcamera, a laptop computer, a digital broadcasting device, a PDA(Personal Digital Assistant), a PMP (Portable Multimedia Player), and anavigation device, but not limited hereto. Thus, any kind of device tophotograph a picture or motion picture may be the optical apparatus.

The optical apparatus according to an exemplary embodiment may include amain body (not illustrated in the drawings), a display unit (notillustrated in the drawings) configured to display information by beingarranged at a surface of the main body, and a camera (not illustrated inthe drawings) having a camera module (not illustrated in the drawings)configured to photograph a picture or motion picture by being installedat the main body.

Hereinafter, a structure of the camera module according to an exemplaryembodiment will be described.

The camera module may include a lens driving device (not illustrated inthe drawings), a lens module (not illustrated in the drawings), aninfrared cut-off filter (not illustrated in the drawings), a printedcircuit board (not illustrated in the drawings), an image sensor (notillustrated in the drawings), and a controller (not illustrated in thedrawings).

The lens module may include at least one lens (not illustrated in thedrawings) and a lens barrel accommodating the at least one lens.However, one structure of the lens module is not limited to the lensbarrel, but any kind of holder structure capable of supporting the atleast one lens may be available. The lens module may move along with alens driving device by being coupled to the lens actuating unit. As anexample, the lens module may be screw-coupled to the lens drivingdevice. As another example, the lens module may be coupled to the lensdriving device using an adhesive (not illustrated in the drawings).Meanwhile, light that has passed through the lens module may beirradiated to an image sensor.

The infrared cut-off filter may block light in an infrared area frombeing incident on the image sensor. As an example, the infrared cut-offfilter may be disposed between the lens module and the image sensor. Theinfrared cut-off filter may be installed at a base (20) to be describedhereinafter. The infrared cut-off filter may be coupled to a holdermember (not illustrated in the drawings). The infrared cut-off filtermay be installed at a through-hole formed on a center portion of thebase (20). As an exemplary embodiment, the infrared cut-off filter maybe formed of a film material or a glass material. Meanwhile, as anexemplary embodiment, the infrared cut-off filter may be formed by aprocess where a kind of infrared cut-off coating material is coated on aflat optical filter such as a cover glass for image plane protection.

The printed circuit board may support the lens driving device. The imagesensor may be mounted on the printed circuit board. As an example, theimage sensor may be disposed at an internal side of an upper surface ofthe printed circuit board, and a sensor holder (not illustrated in thedrawings) may be disposed at an external side of an upper surface of theprinted circuit board. The lens driving device may be disposed at anupper side of the sensor holder.

Alternatively, the lens driving device may be disposed at an externalside of an upper surface of the printed circuit board, and the imagesensor may be disposed at an internal side of an upper surface of theprinted circuit board. Through such structure, the light that has passedthrough the lens module coupled at an inner side of the lens actuatingunit may be irradiated to the image sensor mounted on the printedcircuit board. The printed circuit board may supply electric power tothe lens driving device. Meanwhile, the controller for controlling thelens driving device may be disposed at the printed circuit board.

The image sensor may be mounted on the printed circuit board. The imagesensor may be disposed to have the same optical axis with the lensmodule. Through such structure, the image sensor may obtain the lightthat has passed through the lens module. The image sensor may output theirradiated light as a picture. As an example, the image sensor may beany one of a CCD (charge coupled device), an MOS (metal oxidesemi-conductor), a CPD (charge priming device) and a CID (chargeinjection device), but not limited hereto.

The controller may be mounted on the printed circuit board. Thecontroller may be disposed at an external side of the lens drivingdevice. Alternatively, controller may be disposed at an internal side ofthe lens driving device. The controller may control direction, intensityand amplitude of electrical current supplied to each structural elementforming the lens driving device. The controller may control the lensdriving device to perform at least any one of auto focus function orhandshake compensation function of the camera module. That is, thecontroller may control the lens driving device to move the lens modulein an optical axis direction or in a direction perpendicular to theoptical axis direction, or to tilt the lens module. Furthermore, thecontroller may perform feedback control of the auto focusing functionand the handshake compensation function.

More particularly, the controller may receive a position of a bobbin(30) or a holder member (40) detected by the sensor unit (100), tocontrol electric power or current applied to a first coil (31) and asecond coil (23). Thereby, more precise auto focus function and/orhandshake compensation function can be provided.

Hereinafter, a structure of a lens driving device according to anexemplary embodiment will be described with reference to the encloseddrawings.

FIG. 1 is a schematic perspective view illustrating a camera moduleaccording to an exemplary embodiment; FIG. 2 is an exploded perspectiveview of FIG. 1; and FIG. 3 is a cross-sectional view illustrating a lensdriving device according to an exemplary embodiment.

The lens driving device according to an exemplary embodiment may includea first lens driving unit and a second lens driving unit. Here, thefirst lens driving unit may be a lens driving unit for auto-focusingfunction, and the second lens driving unit may be a lens driving unitfor handshake compensation function.

As illustrated in FIG. 2, the first lens driving unit may include a base(20), a bobbin (30), and a holder member (40). In addition, the firstlens driving unit may further include a cover member (60) forming anouter contour of the camera module. Here, the holder member (40)supporting a magnet (41) (to be described hereinafter) may be arrangedan internal side of the cover member (60).

The base (20) may be coupled to the cover member (60).

The bobbin (30) may be installed in an internal space of the covermember (60), as being reciprocatively movable in an optical axisdirection. A first coil (31) may be installed in a coil accommodatingportion formed on an outer circumferential surface of the bobbin (30).

An upper (51) and a lower elastic member (52) may be installed on anupper portion and a lower portion of the bobbin (30), respectively. Anend of the upper elastic member (51) may be connected to the bobbin(30), and another end of the upper elastic member (51) may be coupled tothe holder member (40), but not limited hereto. The other end of theupper elastic member (51) may be coupled to the cover member (60), ascircumstances require. The other end of the upper elastic member (51)may be coupled to an upper surface or a lower surface of the holdermember (40), when coupled to the holder member (40). An end of the lowerelastic member (52) may be connected to the bobbin (30), and another endof the lower elastic member (51) may be coupled to an upper surface ofthe base, or may be coupled to a lower surface of the holder member(40).

In addition, a protrusion may be formed on a lower side of the base (20)so as to couple the lower elastic member (52). A hole or recess may beformed on the lower elastic member (52), on a position corresponding tothe position of the protrusion, so as to fix the lower elastic member bythe coupling between the protrusion and the hole or recess. In addition,an adhesive may be additionally used for stronger coupling. Theprotrusion and the elastic member may be coupled to each other bythermos-welding.

Meanwhile, as illustrated in FIG. 2, the upper elastic member (51) maybe provided as two springs in a bi-divisional structure. The lowerelastic member (52) may be formed a single body, so as to function as aterminal to be applied with current. That is, the current appliedthrough a terminal (not illustrated in the drawings) may be deliveredthrough two springs of the upper elastic member (52), and the deliveredcurrent may be applied to the first coil (31) wound on the bobbin (30).To this end, the upper elastic member (51) and the first coil (31) maybe conductively connected using a method such as soldering,respectively.

Here, the upper elastic member (51) may include an external portioncoupled to the holder member (40), an internal portion coupled to thebobbin, and a connecting portion connecting the internal portion and theexternal portion. The internal portion may be electrically connected toboth distal ends of the first coil (31) via soldering. That is, the bothdistal ends of the two springs and the first coil (31) may beelectrically connected using means such as soldering, Ag epoxy, welding,conductive epoxy, etc. However, the present disclosure is not limitedhereto. Otherwise, in a reverse way, the lower elastic member (53) maybe formed in a bi-divisional structure, and the upper elastic member(51) may be formed in a single body.

A bidirectional movement in an optical axis direction by the bobbin (30)may be supported by the upper and the lower elastic member (51, 52).That is, the bobbin (30) may be spaced apart from the holder member (40)at a predetermined distance, such that the bobbin (30) can be controlledto move upward and downward from an initial position of the bobbin (30)as a center. In addition, the initial position of the bobbin (30) maycontact a lower surface of the holder member (40), such that the bobbin(30) can be controlled to move only upward from the initial position ofthe bobbin (30).

Meanwhile, the first coil (31) may be provided as a ring-shaped coilblock coupled to an outer circumferential surface of the bobbin (30),but not limited hereto. That is, the first coil (31) may be directlywound on an outer circumferential surface of the bobbin (30). Asillustrated in FIG. 2, the first coil (31) may be installed at aposition near to a lower surface of the bobbin (30), and may include astraight surface and a curved surface according to the shape of thebobbin (30).

In addition, the first coil (31) formed as a coil block may be in anangular shape, and may be in an octagonal shape. That is, the first coil(31) may be all formed of straight surfaces with no curved surface. Thisis by consideration of electromagnetic interaction with the magnet (41)disposed oppositely. That is, the electromagnetic force may be maximizedwhen both surfaces of the magnet (41) and the first coil (31) facingeach other are all flat surfaces. However, the exemplary embodiment isnot limited hereto. The surfaces of the magnet (41) and the first coil(31) may be formed as all curved surfaces, all flat surfaces, or one ascurved surfaces and the other as flat surfaces, according to its designspecification.

In addition, the bobbin (30) may include a first surface flatly formedon a surface responding to the straight surface of the first coil (31)and a second surface roundly formed on a surface responding to thecurved surface of the first coil (31), such that the first coil (31) canbe coupled to an outer circumferential surface of the bobbin (30), butnot limited. That is, the second surface may be also formed as a flatsurface.

The holder member (40) may be formed as a frame roughly in a shape ofhexahedron. Coupling structures for the upper and the lower elasticmember (51, 52) to be coupled may be provide on an upper and a lowersurface of the holder member (40), respectively. A magnet (41) may beinstalled at four edge portions of the holder member (40). Here, asillustrated in FIG. 2, an accommodating portion (not illustrated in thedrawings) may be formed at a position in which the magnet (41) is to beinstalled. However, the present disclosure is not limited hereto. Thatis, the magnet (41) may be adhesively fixed directly to an innercircumferential surface of the holder member (40). The magnet (41) maybe fixed by bonding on a lateral surface or on an edge of the holdermember (40), when the magnet (41) is directly fixed to the holder member(40) in such way as described in the above. In addition, the magnet (41)may be arranged at a plane surface portion of the holder member (40),instead of being arranged at an edge portion of the holder member (40).The magnet (41) will be described again hereinafter.

In addition, according to an exemplary embodiment, the lens drivingdevice may include only a cover member (60), without including aseparate holder member (40), in a case where the lens driving device isprovided not for the handshake compensation function but for the autofocusing function. The cover member (60) may be formed of a metallicmaterial which is a ferromagnetic substance such as iron. In addition,the cover member (60) may be provided in an angular shape when viewedfrom the above, so as to cover a whole of the bobbin (30). Here, asillustrated in FIGS. 1 and 2, the cover member (60) may be in aquadrilateral shape. Alternatively, although it is not illustrated inthe drawings, the cover member (60) may be provided in an octagonalshape. In addition, the magnetic field emitted from edges of the holdermember (40) may be minimized, in case that the cover member is in anoctagonal shape when viewed from the above and the magnet arranged at anedge of the holder member (40) is in a trapezoid shape when viewed fromthe above.

According to an exemplary embodiment, as illustrated in FIG. 3, themagnet (41) may be formed in an asymmetric magnetization structure. Themagnet (41) may include first to fourth magnet portions (41 a)(41 b)(41c)(41 d). Here, the first magnet portion (41 a) and the second magnetportion (41 b) may be arranged at an upper portion of the magnet (41),and the third magnet portion (41 c) and the fourth magnet portion (41 d)may be arranged at a lower portion of the magnet (41). Here, the size ofthe first magnet portion (41 a) and the second magnet portion (41 b) maybe formed relatively smaller than the size of the third magnet portion(41 c) and the fourth magnet portion (41 d).

In addition, the first magnet portion (41 a) and the second magnetportion (41 b) may be magnetized in polarities different from eachother. The third magnet portion (41 c) and the fourth magnet portion (41d) may also be magnetized in polarities different from each other. Here,the first magnet portion (41 a) and the third magnet portion (41 c) maybe arranged outward of the magnet (41), to face the cover member (60).The second magnet portion (41 b) and the fourth magnet portion (41 d)may be arranged inward of the magnet (41), to face an outercircumferential surface of the bobbin (30).

Among the first to fourth magnet portions (41 a)(41 b)(41 c)(41 d), eachof the magnet portions adjacent to each other may respectively have apolarity different from each other. As an example, as illustrated inFIG. 3, the second magnet portion (41 b) may be magnetized in S-pole,while the first magnet portion (41 a) is magnetized in N-pole. At thesame time, the third magnet portion (41 c) may be magnetized in S-pole,while the fourth magnet portion (41 d) is magnetized in N-pole. However,the present disclosure is not limited hereto. The first to fourth magnetportions (41 a)(41 b)(41 c)(41 d) may be magnetized in reverse order, aslong as each of the magnet portions adjacent to each other respectivelyhas a polarity different from each other.

In addition, the lens driving device according to an exemplaryembodiment may include a sensor unit (100) detecting motions of thebobbin (30).

The sensor unit (100) may include a detection sensor (110) and asubstrate (120) on which the detection sensor (110) is to be mounted.The detection sensor (110) may include a Hall sensor (Hall IC), but notlimited hereto. Thus, any sensor capable of detecting magnetic force maybe provided as the detection sensor (110). The detection sensor (110)may be installed at an outer circumferential surface of the bobbin (30).According to an exemplary embodiment, the detection sensor (110) may bearranged at an upper side of the first coil (31). Furthermore, thedetection sensor (110) may be arranged such that a boundary line betweenthe second magnet portion (41 b) and the fourth magnet portion (41 d) isaligned to a center of the detection sensor (110).

Here, the detection sensor (110) may include a sensing portion detectingmagnetic force and a housing accommodating the sensing portion. Thecenter of the detection sensor (110) may be defined as the center of thesensing portion, or may be defined as the center of the housing. Here,the center position of the detection sensor (110) may be marked by amarker at the center position of the housing, such that the centerposition can be easily found from the outside.

Meanwhile, in arranging the boundary line to be a center of the sensingportion of the detection sensor (110), the boundary line may be arrangedclose to the center in some degree, even though the boundary line is notexactly aligned to the center of the detection sensor (110). The centerof the detection sensor (110) may be disposed on a virtual straight lineextended from a boundary line between the second magnet portion (41 b)and the fourth magnet portion (41 d). Alternatively, the center of thedetection sensor (110) may be arranged adjacent to the virtual straightline extended from a boundary line between the second magnet portion (41b) and the fourth magnet portion (41 d).

Via such structure, the detection sensor (110) may be operated inbipolar mode to detect motions of the second magnet portion (41 b) andthe fourth magnet portion (41 d) more effectively. In addition, thecenter line of the detection sensor (110) may be aligned based on theboundary line between the second magnet portion (41 b) and the fourthmagnet portion (41 d) during assembly stage. Thereby, the product can beassembled more precisely.

Meanwhile, the first lens driving unit may be formed as described in theabove. Alternatively, the first lens driving unit may be replaced withan optical system implementing auto-focusing function having anotherstructure rather than the structure described in the above. That is, thefirst lens driving unit may be formed of an optical module using asingle-lens moving actuator, a liquid lens actuator or an actuator ofvariable reactive index type, instead of using an auto-focusing actuatorof voice coil motor type. That is, any kind of optical actuator which isable to perform auto-focusing function may be used in the first lensdriving unit.

Meanwhile, the second lens driving unit may be a lens driving unit forhandshake compensation function. The second lens driving unit mayinclude a first lens driving unit, a base, a lateral support member(42), a first circuit board (21), a second coil (23), and a secondlocation detection sensor (21 a). Alternatively, the second lens drivingunit may include a second circuit board (22), such that the second coil(23) is arranged at the second circuit board (22).

According to an exemplary embodiment, a control element to drive thelens driving device may be installed at the first circuit board (21). Asecond coil (23) in a pattern shape may be formed on the second circuitboard (22). The first and the second circuit board (21, 22) may beconductively connected to each other. The second circuit board (22) maybe arranged by being laminated on an upper side of the first circuitboard (21). However, the present disclosure is not limited hereto. Onlythe first circuit board (21) may be provided, and the second circuitboard (22) may be omitted. In such case, the second coil (23) may beassembled on the first circuit board (21) as a separate component. Asillustrated in FIG. 2, the first circuit board (21) may be provided asan FPCB (Flexible Printed Circuit Board), and may be installed at anupper surface of the base (20).

As illustrated in FIG. 2, the second circuit board (22) may be laminatedon an upper surface of the first circuit board (21), and may adhere tothe first circuit board (21).

The second coil (23) may move shift the whole of the first lens drivingunit to be moved in a flat surface direction perpendicular to theoptical axis, via an interaction with the magnet (41). As illustrated inFIG. 2, the second coil (23) may be formed on the second circuit board(22) by a pattern coil method. The second coil (23) may be arranged ateach of edge portions of the second circuit board (22), as a positionresponding to that of the third magnet portion (41 c) and the fourthmagnet portion (41 d) arranged at a bottom surface of the magnet (41).

As described in the above, according to an exemplary embodiment, thetime required for auto-focusing operation and handshake compensationoperation may be reduced, because motions of the bobbin (30) in theoptical axis direction can be received as a feedback using the sensingunit (100).

In addition, according to an exemplary embodiment, the magnet (41) canbe configured in asymmetric magnetization structure including the firstto fourth magnet portion (41 a˜41 d) having polarities different fromeach other, while the installation position of the detection sensor(110) is center-aligned to the boundary line between the second magnetportion (41 b) and the fourth magnet portion (41 d). Thereby, it isadvantageous to position the detection sensor (110) during the assemblyprocess.

In addition, according to an exemplary embodiment, the higher Halloutput may be obtained by the bipolar-magnetized magnet. Thereby, thedetective precision can be enhanced.

In addition, according to an exemplary embodiment, theasymmetric-magnetized magnet (41) may be used such that the first coil(31) can be formed of a unidirectional coil. Therefore, it isadvantageous for winding up of the coil.

Meanwhile, according to an exemplary embodiment, the lens driving deviceformed as illustrated in FIGS. 1 to 3 may be controlled by bothunidirectional and bidirectional control. That is, the base (20) and thebobbin (30) may be arranged by adhering onto their initial position. Forexample, a stopper may be form the initial position by being protrudedon the holder member (40) and contacting with a bottom surface of thebobbin (30). Alternatively, although it is not illustrated in thedrawings, the stopper may be protruded on the bottom surface of thebobbin (30) and may be arranged by contacting with an upper surface ofthe base (20). In addition, a predetermined prepress may be applied tothe upper and the lower elastic member (51, 52), such that the initialposition of the bobbin (30) can adhere to the base (20), in a case wherethe lens driving device is controlled by the unidirectional control.Thus, the bobbin (30) may move upward by the electromagneticinteraction, when electric power is applied. Otherwise, the bobbin (30)may return to the initial position by the restoring force of the upperand the lower elastic member (51, 52), when the electric power is shutoff. Here, the upper and lower elastic member (51, 52) may be alsoreferred to as ‘first support member’, and the lateral support member(42) may be also referred to as ‘second support member’.

Alternatively, the base (20) and the bobbin (30) may be arranged bybeing spaced apart from the initial position at a predetermineddistance. In such case, the upper and lower elastic member (51, 52) maybe formed in a flat shape with no prepress applied. Otherwise, the upperand lower elastic member (51, 52) may be formed with a predeterminedprepress applied. In such case, the bobbin (30) may move upward ordownward according to the polarity of current, when the electric poweris applied in the initial state where the bobbin (30) is spaced apartfrom the base (20) at a predetermined distance. That is, the bobbin (30)may ascend from the initial position as a standard, when normal currentis applied. In addition, the bobbin (30) may descend from the initialposition as a standard, when reverse current is applied.

As described in the above, according to an exemplary embodiment, timerequired for the auto-focusing operation may be minimized in performingauto-focusing function by controlling the bobbin (30) to ascend upwardor descend downward, because more accurate position of the bobbin (30)can be detected using the detection sensor (110).

The camera module may include a lens driving device formed as describedin the above, a lens barrel (not illustrated in the drawings) coupled tothe bobbin (30), and a printed circuit board (10). Here, an image sensormay be mounted on the printed circuit board. The printed circuit boardmay form a bottom surface of the camera module.

The bobbin (30) may include a lens barrel. At least one lens may beinstalled in the lens barrel. The lens barrel may be screw-coupled to aninside of the bobbin (30), but not limited hereto. The lens barrel maybe fixed to an inside of the bobbin (30) by other means than thescrew-coupling. Alternatively, one or more lenses may be integrallyformed with the bobbin (30) as a single body, without including the lensbarrel. The lens may be formed of a single piece, or otherwise, may beformed of two or more lenses composing an optical system.

The base (20) may further include an infrared cut-off filter installedat a positon responding to that of the image sensor. The base (20) maybe coupled to the holder member (40). In addition, the base (20) maysupport a lower side of the holder member (40). A separate terminalmember may be installed on the base (20), in order for conductivity withthe printed circuit board. The terminal may be integrally formed withthe base (20) using such as surface electrodes. Meanwhile, the base (20)may function as a sensor holder to protect the image sensor. In suchcase, a protrusion may be formed in a downward direction along a lateralsurface of the base (20). However, this is not an essential structure.Therefore, although it is not illustrated in the drawings, a separatesensor holder may be arranged at a lower portion of the base (20) andfunction as the sensor holder.

In the above, exemplary embodiments of the present disclosure have beendescribed. However, these embodiments are merely examples and do notlimit the present invention, so that persons who skilled in the art ofthe present disclosure may easily transform and modify within the limitof the technical spirit of the present disclosure. For example, each ofthe components shown in detail in the embodiments of the presentinvention may be implemented in transformation. In addition, thedifferences relating these transformations and modifications shall beregarded to be included in the scope of the present disclosure asdefined in the attached claims of the present disclosure and theequivalents thereof.

What is claimed is:
 1. A lens driving device, comprising: a cover membercomprising an upper plate and a lateral plate extending from the upperplate; a bobbin disposed in the cover member; a holder member disposedbetween the bobbin and the cover member; a first coil disposed on thebobbin; a magnet disposed on the holder member; a base disposed underthe bobbin and coupled to the lateral plate of the cover member; and asensor disposed on the bobbin, wherein the magnet comprises a firstmagnet part and a second magnet part disposed under the first magnetpart, wherein the first magnet part comprises an inner surface having afirst polarity and an outer surface having a second polarity differentfrom the first polarity, wherein the second magnet part comprises aninner surface having the second polarity and an outer surface having thefirst polarity, wherein a length of the second magnet part in adirection of an optical axis is greater than a length of the firstmagnet part in the direction of the optical axis, wherein the secondmagnet part is disposed between the first magnet part and the base,wherein at least a portion of the sensor faces a neutral boundary of themagnet formed between the first magnet part and the second magnet part,and wherein the first coil faces the second magnet part such that alower portion of the first coil is lower than the neutral boundary ofthe magnet.
 2. The lens driving device of claim 1, wherein the sensor isoverlapped with at least a portion of the first magnet part in adirection perpendicular to the optical axis.
 3. The lens driving deviceof claim 1, wherein an upper surface of the first magnet part comprisesa first region extending from the inner surface of the first magnet partand having the first polarity and a second region extending from theouter surface of the first magnet part and having the second polarity,and wherein a lower surface of the second magnet part comprises a thirdregion extending from the inner surface of the second magnet part andhaving the second polarity, and a fourth region extending from the outersurface of the second magnet part and having the first polarity anddisposed outside the third surface.
 4. The lens driving device of claim3, wherein an area of the third region corresponds to an area of thefourth region.
 5. The lens driving device of claim 1, wherein the firstcoil is overlapped with the second magnet part in a directionperpendicular to the optical axis.
 6. The lens driving device of claim5, wherein the first coil is not overlapped with the first magnet partin the direction perpendicular to the optical axis.
 7. The lens drivingdevice of claim 1, wherein at least a portion of the sensor faces thefirst magnet part.
 8. The lens driving device of claim 1, comprising: acircuit board disposed on an upper surface of the base and comprising asecond coil facing the magnet, wherein the second coil faces a lowersurface of the second magnet part.
 9. The lens driving device of claim8, comprising: an upper elastic member coupled to an upper portion ofthe holder member and an upper portion of the bobbin; and a lowerelastic member coupled to a lower portion of the holder member and alower portion of the bobbin, wherein the first coil is electricallyconnected to the upper elastic member by soldering or Ag epoxy.
 10. Thelens driving device of claim 9, comprising: a support member supportingthe holder member with respect to the base.
 11. The lens driving deviceof claim 1, comprising: a substrate disposed on the bobbin, wherein thesensor is disposed on the substrate.
 12. The lens driving device ofclaim 11, wherein sensor is disposed over the first coil.
 13. The lensdriving device of claim 1, wherein the magnet comprises four magnets,and wherein the four magnets are disposed on four corners of the holdermember, respectively.
 14. The lens driving device of claim 1, whereinthe magnet comprises four magnets, and wherein the four magnets aredisposed on four lateral parts the holder member, respectively.
 15. Thelens driving device of claim 1, wherein the first magnet part and thesecond magnet part are integrally formed.
 16. The lens driving device ofclaim 1, wherein the first polarity is an N-polarity, and the secondpolarity is an S-polarity.
 17. A camera module, comprising: the lensdriving device of claim 1; a printed circuit board disposed under thebase of the lens driving device; an image sensor disposed on the printedcircuit board; and a lens coupled to the bobbin of the lens drivingdevice.
 18. An optical apparatus, comprising the camera module of claim17.
 19. A lens driving device, comprising: a cover member comprising anupper plate and a lateral plate extending from the upper plate; a bobbindisposed in the cover member; a holder member disposed between thebobbin and the cover member; a first coil disposed on the bobbin; amagnet disposed on the holder member and facing the first coil; a basedisposed under the bobbin and coupled to the lateral plate of the covermember; and a sensor disposed on the bobbin, wherein the magnetcomprises a first magnet part and a second magnet part disposed underthe first magnet part, wherein the first magnet part comprises an innersurface having a first polarity and an outer surface having a secondpolarity different from the first polarity, wherein the second magnetpart comprises an inner surface having the second polarity and an outersurface having the first polarity, wherein a distance between an uppersurface of the second magnet part and a lower surface of the secondmagnet part is greater than a distance between an upper surface of thefirst magnet part and a lower surface of the first magnet part, whereinthe second magnet part is disposed between the first magnet part and thebase, and wherein at least a portion of the sensor faces the firstmagnet part.
 20. The lens driving device of claim 19, wherein the sensoris overlapped with at least a portion of the first magnet part in adirection perpendicular to an optical axis.